INFO. ON SLIP YOKE REPLACEMENT AND U-JOINT SERVICING. Chevrolet Astro

SUBJECT: INFORMATION ON SLIP YOKE REPLACEMENT AND U-JOINT SERVICING

MODELS: 1995 AND PRIOR LIGHT DUTY TRUCKS

U-JOINTS THAT ARE PRESSED OUT OF THE PROPELLER SHAFT OR SLIP YOKE MUST NOT BE RE-USED. WHEN IT IS NECESSARY TO PRESS OUT THE U-JOINT TO REPLACE A SLIP YOKE, A NEW U-JOINT MUST BE INSTALLED. A NEW U-JOINT IS NECESSARY AS THE BEARING CUP SEALS AND SLINGERS ARE EASILY DAMAGED. IF THESE COMPONENTS ARE DAMAGED, DIRT AND WATER CAN CONTAMINATE THE BEARING CAUSING EARLY BEARING WEAR-OUT. REPLACEMENT OF THE REAR U-JOINT IS NOT REQUIRED IF THE RETAINING STRAPS HOLDING THE U-JOINT TO THE REAR AXLE PINION FLANGE ARE REMOVED.

LIGHT DUTY TRUCKS MAKE USE OF THREE TYPES OF YOKES: 1. VENTED SLIP YOKE. THIS YOKE CAN BE IDENTIFIED BY A SMALL HOLE IN THE CENTER OF THE SLIP YOKE WELCH PLUG. THIS YOKE USES GREASE FOR INTERNAL LUBRICATION. THE INTERNAL SPLINES OF THE YOKE SHOULD BE COATED WITH A LIGHT COVERING OF GREASE BEFORE INSTALLATION TO THE OUTPUT SHAFT. A SMALL AMOUNT OF GREASE MAY BE FORCED FROM THE VENT HOLE DURING OPERATION. NO ATTEMPTS SHOULD BE MADE TO PLUG THE VENT HOLE. 2. NON-VENTED SLIP YOKE. THIS YOKE HAS NO VENT HOLE AND RELIES ON TRANSMISSION OR TRANSFER CASE FLUID FOR INTERNAL LUBRICATION. GREASE SHOULD NOT BE USED ON THE YOKE INTERNAL SPLINES AS IT MAY CONTAMINATE THE TRANSMISSION OR TRANSFER CASE FLUID. 3. BOLTED OR FIXED YOKE. THIS YOKE DOES NOT SLIDE SO IT NEEDS NO INTERNAL LUBRICATION.

THE TRANSMISSION/TRANSFER CASE OUTPUT SHAFT SEAL SHOULD BE INSPECTED FOR DAMAGE BEFORE INSTALLING THE YOKE. THE SEAL LIPS SHOULD ALSO BE GREASED BEFORE YOKE INSTALLATION FOR LONGER SEAL LIFE AND BETTER PERFORMANCE.

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GENERAL MOTORS BULLETINS ARE INTENDED FOR USE BY PROFESSIONAL TECHNICIANS, NOT A "DO-IT-YOURSELFER". THEY ARE WRITTEN TO INFORM THOSE TECHNICIANS OF CONDITIONS THAT MAY OCCUR ON SOME VEHICLES, OR TO PROVIDE INFORMATION THAT COULD ASSIST IN THE PROPER SERVICE OF A VEHICLE. PROPERLY TRAINED TECHNICIANS HAVE THE EQUIPMENT, TOOLS, SAFETY INSTRUCTIONS AND KNOW-HOW TO DO A JOB PROPERLY AND SAFELY. IF A CONDITION IS DESCRIBED, DO NOT ASSUME THAT THE BULLETIN APPLIES TO YOUR VEHICLE, OR THAT YOUR VEHICLE WILL HAVE THAT CONDITION. SEE A GENERAL MOTORS DEALER SERVICING YOUR BRAND OF GENERAL MOTORS VEHICLE FOR INFORMATION ON WHETHER YOUR VEHICLE MAY BENEFIT FROM THE INFORMATION.